维生素是维持动物健康、促进动物生长发育所必需的一类低分子有机化合物。这类物质在水产动物体内不能由其他物质合成或合成量很少,必须经常由饲料提供。但动物体对其需要量很少,每日所需量仅以毫克或微克计算。维生素虽不是构成动物体 Vitamin is a kind of low molecular weight organic compound which is necessary for maintaining animal health and promoting animal growth and development. Such substances in aquatic animals can not be synthesized from other substances or synthetic amount is very small, must often be provided by feed. However, the animal body needs a small amount of daily amount required only in milligrams or micrograms. Although vitamins do not constitute animal body